Fire-alarm switch



G. F. MILLER.

FIRE ALARM SWITCH. APPLICATION FILED MAYZY, 919.

1,340,729. Patented M y 18, 1920.

WITNESSES I 11v VENTOR day. 1 .Aia'ller,

' ATTORNEYS UNITED STATES PATENT OFFICE.

GUY F. MILLER, OF TRAVERSE CITY, MICHIGAN.

FIRE-ALARM SWITCH.

To alt whom it may concern Be it known that I, GUY F. MILLER, a

citizen of the United" States, and a resident of Traverse City, in the county of Grand Traverse, in the State of Michigan, have invented a new and Improved Fire-Alarm Switch, of which the following is a full, clear, and exact description. v v

. This invention relates to automatic fire alarms and has particular reference to switches involving the use of some fusible device which normally holds the switch points separated, but which when in proximity to high temperature such as may be incident to the starting of a fire in a building will burn or so weaken as to permit the switch points to come together and complete a circuit which may include any suitable audible, or other alarm devices.

Among'the objects of the invention 1S to provide a fire alarm switch of an unusually simple, cheap, and yet efiicient nature; one which may be introduced at any point or points along a double twisted insulated wire so that the presence of fire or dangerous heat in any part of a building may make itself manifest at such place and a record indicated thereof at any desired headquarters such as an-ofiice, sleeping apartment, or watchmans station, and a further object is to provide a safety switch of the character indicated that is adapted to be easily manipulated in installation and which will retain its virtue throughout a long period of years.

With the foregoing and other objects in view the invention consists in the arrangement and combination of parts hereinafter described and claimed, and while the invention is not restricted to the exact details of construction disclosed or suggested herein, still for the purpose of illustrating a practical embodiment thereof reference is had to the accompanying drawings in which like reference characters designate the same parts in the several views, and in which- Figure 1 is a perspective view of the safety switch prior to its attachment to the line wires and with the dust protecting cap omitted.

Fig. 2 is a plan view of the same after it is attached to the line wires but before taping; and

Fig 3 is a detail view in longitudinal section indicating the normal relation of the two switch points or blades.

Specification of Letters Patent. Patented May 18, 1920, Application filed May 27,

1919. Serial No. 300,068.

Referring now. more specifically to the drawings I show my invention as comprising a block or body 10 of fiber, porcelain, hard rubber, or other suitable durable insulation. Said body is'indicated as rectangular in general form and'provided alongone side with a long recess or notch 11.

12 indicates a stationary switch blade fastened in any suitable manner upon one end. of the body 10 and having a lip 12 bent inward into the recess 11 adjacent to one end of the recess. The edge however of the lip is spaced materially from the bottom of the recess. The other switch blade is indicated at 13 one end of which is secured upon the opposite end of the body 10 from the blade 12 while the main portion of the blade 13 extends along the recess 11 and with its free end lying within the space between the lip 12' and the bottom of the recess and spaced from the aforesaid edge of said lip. Any suitable material of good conductivity may be used for these blades but I prefer phosphor bronze because such material is well rigid blade 12. To this end I employ a clip 14 shown as in the form of a U straddling the middle portion of the body and having the legs thereof extending past the edges of the blade 13 and connected to an inflammable retainer 15 shown as in the form of a fiat piece of celluloid having reduced ends or points 15. This retainer lies fiat against the outer face of the blade 13 and is preferably provided with holes 16 through which the leg portions of the clip 14 are passed and clenched orbent over on the outer face of the retainer. This clip may be made of wire or any other suitable material strong enough to hold the retainer close enough to the body 10 to keep the points of the springs separated as clearly shown in Fig. 3. The celluloid strip or its equivalent constituting the retaineris sufficiently stiff and strong to hold indefinitely to intended shape and prevent the contact between the two blades 12 and 13. The clip 14 is of a permanent nature and so the device will retain the form or position indicated indefinitely. In order to prevent the accumulation of dust on or between the contact points or any other conditions that might prevent the proper operation of the swltch in case of an emergency I provide a covering which may be in the nature of a cap 17 made of thin sheet celluloid or other inflammable material but of a permanent nature when not exposed to heat. This cap is fitted over the recessed portion of the body, the adjacent contact points,- the clip, and the main portion of the retainer, leaving however the points 15 of the retainer projecting and exposed. The shape otthc body-and the portions of the blades rigidly secured to its ends adapt the cap for fitting closely so as to carry out the purpose thereof.

As one means for securing the contact blades to the body I provide for each of them a conductor wire 18 one end of which is passed through the fixed end of the blade and the adjacent end of the body and then clenched or otherwise fastened on the opposite side of the body. This conductor serves therefore two immediate purposes,first, to lock the blade in place, and secondly, as a connector between the switch device and a line wire indicated at 19.

All of the parts are .made of relatively cheap, standard, and easily acquired materials and they are formed and assembled with a minimum amount of expense.

In the practice of the invention I employ a double twisted mainline comprising the two wires 19 having a covering of insulation 20 which may be extended for any desired distance or through any number of rooms or apartments. One end of the line wire obviously will be connected with any suit able battery or other source of energy and some alarm device such as a gong which features are so common and well understood that they are not illustrated.

The double wire may be untwisted slightly at any desired point so as to separate the wires 19 each of which will then be stripped for say one-half an inch for the connection of the conductors 18 which may be done by simply twisting the loose ends thereof around the bared wires 19. To make the connections permanent they are preferably soldered and wrapped with tape in the manner well understood in the electrical art. The switch device as a whole is made fiat, and having the conductor or connecting members exposed from the ends of the body it may be easily attached to the line wire as described without any attention on the part of the electrician in installing it. These devices are made and sold so cheaply that they may be inserted in or along the double mally hold said blade wire at every six feet or wherever desired. Obviously the alarm devices may. be so constructed that the location of the fire may be indicated as result of the o eration of any of-the automatic switches. 11 the event of fire in proximity to the 'infiammablematerial 15 or 17, it would be most likel itself manifest at 15, one or bot 1 of such points would become ignited and immediately cause the burning of the retainer 15 and the release of the movable or flexible blade 13 whose tree end would then engage the lip 12 and complete the circuit.

I claim:

l. The herein described safety switch comprising a rigid body of insulation having a recess formed in one side between and remote from the ends of the contact blades secured to the ends of the body on the recessed side and having their ends projecting into the recess, one of the blades being shorter than the other and terminating in a lip directed inward toward the bottom of the recess and spaced there from, the other blade being longer and flexible and having its free end in the space between said'lip and the bottom of the recess, means of a rigid nature embracing the body and the flexible blade and serving to norsaid holding means including an inflammable retainer, means to electrically connect the body and blades to line wires and hold the switch in service, and a protecting device embracing the central portion of the body, the switch points, and the main portions of the holding means for the flexible blade, to prevent failure of the switch because of dust or like conditions.

2. In a safety switch, the combination of a body of insulation, a pair of switch blades secured to remote portions of the body, said blades having ends adapted to engage each other and one of the blades being resilient. a clip embracing the body and the resilient blade, a retainer of inflammable material cooperating with the clip to hold the resilient blade spaced from the other blade whereby when the retainer becomes ignited it will burn and release the resilient blade permitting it to engage the other blade and establish a circuit through them, and connector wires extending through the blades and the body and serving thereby to secure the blades to the body and establish electrical connection between the blades and any devices to which the connectors may be secured.

GUY F. MILLER.

body, a pair of' to make spaced from the lip, 

